ABSTRACT
Objective To is ol ate novel thyroid hormone-response genes, to study the characterizations of the ir expressions and to predict their possible functions in neonatal rats. Methods A neonatal rat model with congenital hypothyr oidism was established and cDNA fragments of novel thyroid hormone-response gen es from cerebral cortex of neonatal rats were obtained by fluorescence-labeled DD-PCR analysis, subcloning and sequencing. Complete cDNAs of novel thyroid hor mone-response genes were cloned by the techniques of electronic clone, RT-PCR and sequencing, their expressions regulated by thyroid hormone were confirmed b y Northern blot analysis, their distributions, transcription levels in different tissues and different brain areas were further observed by semiquantitative RT -PCR analysis, and their possible functions were postulated through bioinformat ic techniques. Results A novel complete cDNA of thyroid hormone-response protein-1 (TRP-1) gene is cloned. It is 973 bp in f ull-length (Gene Bank accession no. AF348365), and its transcription was enhanc ed in cerebral cortex in neonatal hypothyroidism rats. The expression of its mRN A was very extensive, but more abundant in brain. Its transcriptional level in d ifferent brain areas was not uniform, much higher in olfactory bulb. Its encodin g protein had some significant domains and motifs. Conclusion TRP-1 gene is a new thyroid hormone-response gene and may play an important role during normal brain development. Its abnormal expression may b e partially responsible for neurological defects in brain arising from thyroid h ormone deficiency during critical period for perinatal rats.
ABSTRACT
To insight into genetic differences between chloroquine-resistant line (RC) and chloroquine-sensitive strain (N) of Plasmodium berghei. MethodsAfter continous cbloroquine-pressure upon RC line at higher dosage (50mg/kg. d) ,total RNAs from the RC line and the N strain of P. berghei were isolated for simplified differential display reverse transcript polymerase chain reaction (sDDRT-PCR ). The generated differential fragments had been repetitively rescued and identified by PCRs before one pair of suspected differential fragments (N25 and R25 )were cloned and sequenced. Then, their sequences were analyzed through PC-gene program and BLAST search. ResultsThough the identity of two nucleotide sequences of N252 and R251 ,cloned separately from the N25 and R25 fragments, were up to 99.8％ ,their predicted amino acid secondary structures were quite different due to multiple mutations. Compared with the published sequences in GeneBank,EMBL,DDBJ and PDB database ,no similar gene was found ,using BLAST search. However their partial nucleotide sequences (62nt from query 128nt to189nt bore highly homology to part sequence(from 1053nt to1114nt)of rattus norvegicus mRNA for phospholipase B,up to 93.5％ in N251 and 91.9％ in N252 respectively. ConclusionIt is feasible to isolate chloroquine-resistant related genes by using simplified DDRT-PCR combined repetitively rescuing and PCR identifying the interest differential DNAs together with sequence analyses.